The election is not in the bag. Race could still undo Obama

'I am the son of a black man from Kenya and a white woman from Kansas. I was raised with the help of a white grandfather who survived a depression to serve in Patton's army during World War II and a white grandmother who worked on a bomber assembly line at Fort Leavenworth while he was overseas. I've gone to some of the best schools in America and lived in one of the world's poorest nations.

'I am married to a black American who carries within her the blood of slaves and slave owners - an inheritance we pass on to our two precious daughters. I have brothers, sisters, nieces, nephews, uncles and cousins, of every race and every hue, scattered across three continents, and for as long as I live, I will never forget that in no other country on Earth is my story even possible.'

Barack Obama spoke these words in March. That was a long time ago, but the speech is worth recalling because race flows like a Stygian river beneath the American election campaign, surfacing occasionally as it did then because of inflammatory remarks by Obama's controversial Chicago pastor, the Rev Jeremiah Wright, and as it may again on 4 November.

Race cuts several ways. A recent survey found that the first nomination of an African American for President by a major party has prompted a surge in national pride and political engagement among blacks. And there are voters, of all stripes, who will vote for Obama because of his life story - the 'journey' Sarah Palin obliquely mocked in her speech at the Republic national convention - and what they believe it says about the United States.

However, it's also clear from a growing number of studies that some voters will vote against Obama because of his race. Some will cast blatantly racist votes. Others will vote against him because they're not comfortable with him, their votes guided by doubt, an indefinable fear, a queasiness they can't describe. A number of recent studies and polls have shown that the pull of racism is still there. One poll found that one-third of white Democrats and voters registered as independents harbour negative views toward blacks that could affect their voting.

Social science research in the United States reveals just how submerged racial prejudice can be. Writing in the Washington Post, Daniel Kiel of the University of Memphis in Tennessee, said studies on racial attitudes in job-candidate evaluations shed light 'on how race may be affecting our collective judgment', yielding earnest but biased evaluations. When reviewers, he said, compare identical resumes of black and white job applicants, white candidates are rated more highly than black candidates. Paradoxically, he says, the more qualified the candidate is, the greater the rating discrepancy is, which is bad news if you're a black man running for the highest office in the land.

Straightforward political polling often falls far from the mark because of what has become known as the Bradley Effect, which dates to the campaign for the California governorship in 1982. Surveys in the run-up to the election and even exit polls on the day put Tom Bradley, the first black mayor of Los Angeles, well ahead of the Republican candidate. And yet Bradley lost by 1.2 per cent. Why? Speculation pointed in several different directions: inadequate sampling, people changing their minds at the last minute, latent racism that didn't turn up in the polling and outright lying on the part of voters or, at least, a reluctance on the part of people polled to admit a voting preference that they thought might be socially unacceptable.

Obama spent much of his youth exploring the consequences of his race. Being black and white didn't make it any easier. But he knew those consequences could not be ignored. So it was that in March Obama travelled to the National Constitution Centre in Philadelphia and made what I and many others consider to be the finest speech of the 2008 American presidential campaign. Obama was responding to an explosion of publicity surrounding remarks the Rev Wright had made in the past, including 'God damn America' (for bombing Hiroshima) and his suggestion that the US bore some of the responsibility for the 9/11 attacks. Obama saw that both his race and his patriotism were under fire.

Characteristically, for he is nothing if not a lawyerly intellectual and fully cognizant of his rhetorical skills, Obama decided to tackle the Wright imbroglio head-on. In his speech, an excellent exegesis on race in America, Obama condemned Wright's remarks, but did not disown the man. He explained that he could not, because Wright, 'as imperfect as he may be', is 'like family'. Obama said that Wright's church, where Obama was married and his daughters baptised, 'contains in full the kindness and cruelty, the fierce intelligence and the shocking ignorance, the struggles and successes, the love and, yes, the bitterness and bias that make up the black experience in America'.

Obama went on to say: 'The profound mistake of Reverend Wright's sermons is not that he spoke about racism in our society. It's that he spoke as if our society was static; as if no progress has been made; as if this country - a country that has made it possible for one of his own members to run for the highest office in the land and build a coalition of white and black, Latino and Asian, rich and poor, young and old - is still irrevocably bound to a tragic past. But what we know - what we have seen - is that America can change. That is true genius of this nation.'

Obama has been quieter of late, his language more careful, as he directs his appeal to wavering and undecided voters who could well determine the outcome of the election. As the campaign moves into its final weeks and as John McCain's rhetoric turns negative, it's safe to say that this is not going to be the post-racial election that many hoped it would be. American history does not let go that easily. But Obama's lead over McCain is holding firm. All things being equal - if that can be said in the case of a black presidential aspirant - Obama seems justified in clinging to what he called in that speech so many months ago, echoing not only the title of a 1990 Wright sermon but also the title of his second book, 'the audacity of hope'.

• Stryker McGuire is a contributing editor to Newsweek magazine and editor of International Quarterly, a forthcoming journal on world affairs